Telling foreigners about ご祝儀

Hi everybody,

My fiancee (Japanese) and I are getting married soon and we'd like to invite people from work. Japanese people already know about ご祝儀 but foreign people might not. When I suggested just telling them directly about it she said it sounded too rude. I was wondering if anybody has had any experience with it and what would be a smooth way of letting people know about it.

Are you sending out invitations (written or digital?).
Why not write something on the invitations? If you want or expect cash, say something like "shūgi gratefully accepted". If you say that and the recipient is still too obtuse to pick up on it, then maybe don't invite that person, or just accept that there will be a clueless foreigner in the crowd, and be happy that this invitee likes or respects you enough to show up at your wedding. More embarrassing for him/her than for you, and you will have enough on your hands to bother worrying about your clueless guest's embarrassment.

If you are not accepting other types of gifts, just be up front about it. You can tell your foreign friends privately if you think they need the heads up. "We are not using a wedding registry for gifts, but we are accepting the traditional monetary presents." Something like that.

Where are your foreign friends from?

I like Majestic's idea of the hint on the card. Bear in mind that people will generally want to give something. I got married in Japan and we told friends and family coming over from overseas (mainly Britain) that with the high cost of the airfare, we didn't expect anything, but even so most of them insisted on giving us an envelope with cash in it. So if people want to give something, I expect they will be happy with giving cash as it avoids all worries about the suitability of their present.
You might want to think about the amount. that you ask for. I think the customary 3 man is extortionate and we asked for 1 man each from Japanese friends (many of them having kids and also travelling a long distance) and we did not give them the extravagant 'hangaeshi' souvenir gift.